An international group of scientists led by researchers from the National Institute of Astrophysics has revealed for the first time a polarized signal in the intergalactic gas of the galaxy cluster Abell 523 that extends on previously unobserved scales, about eighty times the size of the galaxy. Milky Way .

The team is coordinated by the Cagliari researcher Valentina Vacca , alongside her also Federica Govoni and Matteo Murgia , researchers in the Sardinian observatory.

The polarized signal provides direct evidence of the presence of a weak but large magnetic field pervading the cluster, up to its periphery. The result is published in the Monthly Notices of the Royal Astronomical Society .

Abell 523 is a cluster of galaxies invisible to the naked eye that is about 1.6 billion light years from the Solar System and appears in the sky about halfway between the constellations of Orion and that of Taurus . For the observations, data collected by the Jansky Very Large Array (VLA), a network of radio telescopes built in New Mexico, USA, was used.

"Thanks to the Very Large Array (VLA) - explains Valentina Vacca , researcher of INAF from Cagliari and first author of the study - we were able to observe the polarized emission associated with the intergalactic medium of the Abell 523 cluster and shed light on a phenomenon that was otherwise inaccessible. The polarized emission that we have discovered extends on spatial scales in which the total intensity is not in fact visible ".

"The observations in polarization are little affected by some instrumental limits, for the experts we talk about the confusion limit, compared to those in total intensity. With the same observation time and resolution, polarization observations can reach much higher sensitivities and reveal weak sources that would not otherwise be visible "comments , head of the National Enabling Division for Radio Astronomy of INAF. "However, we thought we had to wait a few decades for the advent of the SKA Observatory. The result we have obtained - says , first researcher of INAF of - is ahead of the times and shows that this type of study can already be carried out with current tools ".